The present invention relates to a quick charging control circuit of a paging receiver and to a process for controlling quick charging of a paging receiver, and more particularly, to a charging control circuit and a process for minimizing occurrence of error during reception of broadcast data by relying upon different operational steps for regulating a quick charging control circuit respectively in response to states of data received.
Generally in contemporary designs, since a paging receiver is operated with the voltage provided by a battery, it has a battery saving circuit for minimizing power consumption by periodically, rather than continuously, supplying power to a radio frequency (RF) receiving circuit.
Typically, contemporary designs of paging receivers contemplate use of a capacitor with a large capacitance, for shaping the waveform of a received radio frequency signal. That capacitor is connected either in series or in parallel, to an input terminal receiving a radio frequency signal. Charging and discharging of the capacitor occurs in response to a battery saving signal, and necessary data can not be reliably obtained from the radio frequency signal with a dependable modicum of accuracy during the charge time constant of the charging stage of the circuit while the capacitor is being charged. Consequently, contemporary designs also rely upon a quick charging circuit for charging the capacitor over a shorter time than the time constant of the charging stage commonly used in the waveform-shaping circuits. Moreover, since the waveform-shaping circuit has a low-pass filter for producing a reference voltage, sufficient time is required for charging the capacitor to raise the amplitude of the reference voltage to correspond to an intermediate voltage of the low pass filter. Therefore, in contemporary designs of paging receivers, the battery saving circuit is periodically operated before a self-identification data frame signal is received; that is, the battery saving circuit is operated with a shorter period than the time constant of the low pass filter. If power is provided to the entire circuit before the self-identification data frame signal is received, unnecessary power is supplied to the parts of the circuit other than the waveform shaping stage for producing the reference voltage, thereby lowering power consumption efficiency. In order to improve such inefficient power consumption, more recent designs of receivers suggest that when first supplied, the reference voltage of the waveform-shaping circuit be applied separately to the radio frequency receding circuit and to the waveform-shaping circuit. An example of such a quick charging control circuit is disclosed by way of example, in U.S. Pat. No. 4,479,261 issued on 23 Oct. 1984 to Taksaki Oda and Takeshi Nakajima.
In operational use of contemporary paging receivers however, if the code length of transmitted data is very long, it is difficult to continually maintain the charged voltage while the entire code length is being received, and an error may consequently be introduced into the data received due to a gradual drop in the charged voltage during the prolonged period required for receiving the transmitted data. In addition, with the typical contemporary paging receiver, if the main power of the receiver is turned off, and consequently the capacitor is fully discharged, even after the main power of the receiver is again turned on, substantial time (i.e., due to the capacitor charging interval) is required before the circuit is able to resume operation. Consequently, an error may be introduced into the data received during the capacitor charging interval immediately after the main power has been turned on.